1. Field of the Invention
The present invention relates to a wafer planarization apparatus for, in a semiconductor wafer manufacturing process, grinding a backside on which no chip of a semiconductor wafer is formed and a planarization method thereof.
2. Description of the Related Art
The planarization apparatus for grinding a backside of a semiconductor wafer is generally comprised of a storing stage for storing the wafer and a grinding stage for grinding it, where the wafer is carried by a sucking and carrying apparatus between the storing stage and the grinding stage.
The sucking and carrying apparatus has a sucking board for sucking and holding the wafer with a suction pad and carries the wafer sucked and held by the suction pad to a wafer chuck table on the grinding stage. And the wafer is ground by a rotating grinding wheel in a state of being sucked and held by the chuck table.
There is a problem that, if the wafer forcefully contacts the chuck table on conveying the wafer from the sucking board to the chuck table, the wafer gets chipped or cracked or a chip gets damaged due to an impact thereof. As for this problem, while there is a method of exerting control by decelerating the wafer conveyance speed on delivering the wafer from the sucking board to the chuck table, this control is very difficult in terms of variations in board thickness of the wafer and assembly errors of the apparatus.
The present invention has been developed in view of the above-described circumstances, and an object thereof is to provide the planarization apparatus of the wafer capable of preventing the wafer from getting damaged on delivering the wafer from the sucking and carrying device to the table and a planarization method thereof.
In order to achieve the above described object, the present invention is directed to a wafer planarization apparatus, comprising: a body; a table which sucks and holds a first surface of a wafer; a sucking and carrying device including a sucking board which sucks and holds the wafer and carries the wafer to the table; and a working division which works on a second surface of the wafer of which the first surface is sucked and held with the table, wherein: the table is placed to be vertically mobile on the body; the wafer before planarization sucked and held with the sucking board is vacuum-attracted when positioned above the table, the table being moved upward by that attraction power in a direction to suck the wafer so as to vacuum-suck the wafer; and when the wafer is vacuum-sucked with the table, the sucking and carrying device releases the sucking and holding of the wafer with the sucking board.
The present invention is also directed to a wafer planarization method, comprising the steps of: sucking and holding, with a sucking board, a wafer before planarization; positioning the wafer sucked and held by the sucking board above a table which is capable of vacuum-attracting the wafer and is placed to be vertically mobile; vacuum-attracting the wafer with the table so that the table is moved upward by that attraction power in a direction to suck the wafer so as to vacuum-suck the wafer; and releasing the sucking and holding of the wafer with the sucking board so that the wafer is only sucked and held with the table.
According to the present invention, the wafer before planarization sucked and held by the sucking board is positioned above the table. Next, the table vacuum-attracts the wafer so that the table is moved upward by that attraction power in the direction to suck the wafer so as to vacuum-suck it. And then, the wafer is only sucked and held by the table by releasing the sucking and holding of the wafer by the sucking board. The conveyance of the wafer from the above described sucking and carrying device to the table is thereby finished. Thus, according to the present invention, the wafer is conveyed to the table not by moving the sucking board by a mechanical feeding apparatus but by moving the table upward by vacuum attraction, so that the wafer can be softly conveyed from the sucking and carrying device to the table without considering variations in board thickness of the wafer and assembly errors of the apparatus. Accordingly, it is possible to prevent the wafer from getting damaged on conveyance thereof.